Pet Drug Reports

Drugs by active ingredient

Drug · single active ingredient

Thiabendazole: adverse event reports

All products with this active ingredient · 17 FDA-approved applications in the Green Book

56reports naming this ingredient, 1987–20140% of all reports · about 1 a year
0reports, 12 months to March 20260 in the 12 months before
50%classed serious, as reportedof 36 reports stating it
7.1%record death or euthanasia, as reported4 reports
37.5%of reports concern dogs0% of all dog reports

56 adverse event reports in FDA's database list a drug whose active ingredient is recorded as thiabendazole. The earliest was received in November 1987, the latest in August 2014. The Green Book lists 17 FDA-approved applications with this single active ingredient.

openFDA masks the brand and manufacturer in every report, so these figures describe the ingredient across all products and cannot be attributed to a brand.

In the 12 months to March 2026, 0 reports named it, and none in the 12 months before. Recent months are provisional: fDA posts reports quarterly with a delay of three to six months, so the newest months are incomplete and usually grow in later releases. Over its whole reporting history that is about 1 reports a year and 0% of all 1,357,245 reports (0% of all dog reports). How many animals received it is not published, so a count says nothing about how often a problem occurs per dose.

Reporters most often listed uncoded sign (25%), death (8.9%) and dropper, Abnormal (8.9%). A report can list several signs, so shares add to more than 100%; 74 different terms appear across these reports. Uncoded sign appears in 25% of these reports, a larger share than in the pooled reports for every drug containing thiabendazole (0.7%).

37.5% of reports concern dogs. Not every report describes illness: 26.8% as product or packaging defects. Of reports that state seriousness, 50% were classed as serious, and 7.1% of all reports record a death or euthanasia as an outcome, as reported. FDA has not necessarily determined whether any drug played a part.

Monthly reports by species, five years

Dog0 · peak 1
2022202320242025
Cat0 · peak 1
2022202320242025
Horse0 · peak 1
2022202320242025
Other0 · peak 1
2022202320242025

Reports by the month FDA received them. Each panel has its own scale; the peak month is printed at the top right. The newest months are incomplete because FDA posts reports with a delay of three to six months.

Reports by year received

016311987: 119871989: 119891990: 119901991: 119911996: 119961999: 119992010: 820102011: 3120112012: 1020122014: 12014

2014 covers reports received through March 2026 only.

Signs listed in reports

share of thiabendazole reports listing the termall drugs containing thiabendazoleall dog reports

  1. Uncoded sign[a sign with no matching dictionary term]25%14
  2. Death8.9%5
  3. Dropper, Abnormal8.9%5
  4. Caps, Abnormal[a product quality report, not a sign in an animal]7.1%4
  5. Vials, Leaking[a product quality report, not a sign in an animal]7.1%4
  6. Accidental exposure[exposure that was not intended]5.4%3
  7. Deafness NOS[NOS: not otherwise specified]5.4%3
  8. External ear disorder NOS[NOS: not otherwise specified]5.4%3
  9. Lethargy[unusually tired or inactive]5.4%3
  10. Anorexia[not eating]3.6%2
  11. Application site erythema[reddened skin where the product was applied]3.6%2
  12. Ataxia[unsteady, uncoordinated movement]3.6%2
  13. Behavioural disorder NOS[behaviour change, type not specified]3.6%2
  14. Diarrhoea[diarrhea]3.6%2
  15. Elevated alanine aminotransferase (ALT)[a liver enzyme above the normal range]3.6%2
  16. Elevated liver enzymes[liver enzymes above the normal range]3.6%2
  17. Tachycardia[fast heart rate]3.6%2
  18. Abnormal birth weight1.8%1
  19. Anaemia NOS[low red blood cell count]1.8%1
  20. Anaphylaxis[sudden severe allergic-type reaction]1.8%1
  21. Application site blister[blister where the product was applied]1.8%1
  22. Application site hair change[hair change where the product was applied]1.8%1
  23. Application site irritation[irritation where the product was applied]1.8%1

Top 30 of 74 coded terms (VeDDRA, the veterinary reporting dictionary; plain-language gloss in brackets). One report can list several terms. The ticks show how often the same term appears in a wider pool of reports; they describe the reports, and FDA cautions that such figures cannot be used to estimate risk or to compare one product with another. openFDA masks brand and manufacturer names in adverse event records, so the reports counted here cannot be attributed to a particular brand.

Outcomes and report types

Outcome recorded in the report

Recovered/Normal16.1%9
Recovered with Sequela1.8%1
Ongoing0%0
Died7.1%4
Euthanized0%0
Outcome Unknown46.4%26

What kind of report it was

Safety issue73.2%41
Lack of expected effectiveness0%0
Both safety and lack of expected effectiveness0%0
Manufacturing or product defect26.8%15
Other0%0

Coloured bar: reports naming thiabendazole. Grey bar: all 1,357,245 reports in the database. Outcomes are the status at the time of the last report, as stated by the reporter; a report covering several animals can carry more than one outcome. FDA has not necessarily determined whether any drug played a part in any outcome.

Species and breeds in the reports

Species

Dog37.5%21
Human exposure14.3%8
Cat12.5%7
Cattle7.1%4
Sheep3.6%2

Single-breed animals

Breed shares follow how common each breed is. Crossbred animals and reports with no breed stay in the species figure only.

Age, weight and route

Age of the animal

Under 1 year7.1%4
1 to 3 years10.7%6
4 to 7 years17.9%10
8 to 11 years7.1%4
12 years and over12.5%7
Age not given44.6%25

Weight of the animal

Under 5 kg (11 lb)12.5%7
5 to 9.9 kg (11–22 lb)12.5%7
10 to 24.9 kg (22–55 lb)10.7%6
25 to 44.9 kg (55–99 lb)8.9%5
45 kg and over (99 lb+)8.9%5
Weight not given46.4%26

Route of administration stated in reports: auricular (otic) (19), ophthalmic (10), oral (7).

In context

MeasureThiabendazoleAll drugs containing thiabendazoleAll dog reportsAll reports
Reports562,045985,6751,357,245
Share of that pool's reports naming this drug—2.7%0%0%
Classed serious, of reports stating it50%36.4%38.3%38.6%
Death or euthanasia recorded, per 1,000 reports71.4575563.8
Filed as lack of expected effectiveness (wholly or partly)0%——23%
Top term, share of reportsUncoded sign 25%0.7%0.1%—

The thiabendazole pool is every report naming thiabendazole alone or in any combination; this single-ingredient set accounts for 2.7% of it. Shares are of reports, not of animals treated. The number of doses sold is not public, so none of these figures is a rate of occurrence, and differences between columns reflect which animals receive a drug and who reports as much as anything else.

Other ingredient sets sharing an ingredient

Active ingredientsReportsLatest 12 months
Dexamethasone + Neomycin Sulfate + Thiabendazole1,088162
Dexamethasone + Thiabendazole90020

Listed for navigation, ordered by report count. FDA states that these data "cannot be used to estimate the risk associated with the product or compare one drug or device product with another": drugs differ in formulation, in the animals they are given to, in sales volume and in years on the market. A report's ingredient field can be incomplete, so reports about one product may sit under more than one set.

FDA-approved products containing thiabendazole (Green Book)

Reference information, not report statistics. openFDA masks brand and manufacturer names in adverse event records, so the reports counted here cannot be attributed to a particular brand. The list below is the FDA Green Book as of 1 Oct 2026; nothing on this page says which of these products, if any, a report concerned.

Trade nameActive ingredientsSponsorApproved forApplication
Thibenzole Sheep & Goat Wormerapproval voluntarily withdrawnThiabendazoleBoehringer Ingelheim Animal Health USA Inc.Sheep, GoatsNADA 013-022
Equizole Horse Wormerapproval voluntarily withdrawnThiabendazoleBoehringer Ingelheim Animal Health USA Inc.HorsesNADA 013-407
Thibenzole 20% Swine Premixapproval voluntarily withdrawnThiabendazoleBoehringer Ingelheim Animal Health USA Inc.SwineNADA 013-954
Omnizoleapproval voluntarily withdrawnThiabendazoleBoehringer Ingelheim Animal Health USA Inc.Cattle, Sheep, GoatsNADA 014-350
TBZ Cattle Wormer (Drench)approval voluntarily withdrawnThiabendazoleBoehringer Ingelheim Animal Health USA Inc.CattleNADA 015-123
TBZ 200 Medicated Feed Premixapproval voluntarily withdrawnThiabendazoleBoehringer Ingelheim Animal Health USA Inc.Cattle, Swine, Sheep, GoatsNADA 015-875
Thibenzole (18 mg)approval voluntarily withdrawnThiabendazoleBoehringer Ingelheim Animal Health USA Inc.CattleNADA 030-103
E-Z-EX Wormer Pelletsapproval voluntarily withdrawnThiabendazoleADM Animal NutritionCattle, Sheep, GoatsNADA 030-578
Equizoleapproval voluntarily withdrawnThiabendazoleBoehringer Ingelheim Animal Health USA Inc.Horses, Cattle, Sheep, GoatsNADA 034-114
Thibenzole Pig Wormerapproval voluntarily withdrawnThiabendazoleBoehringer Ingelheim Animal Health USA Inc.SwineNADA 035-631
Purina Horse Wormer Medicatedapproval voluntarily withdrawnThiabendazoleVirbac AH, Inc.HorsesNADA 040-205
E-Z-EX Wormer Mintrate Blockapproval voluntarily withdrawnThiabendazoleADM Animal NutritionCattleNADA 042-910
Thibenzole 300 Medicatedapproval voluntarily withdrawnThiabendazoleBoehringer Ingelheim Animal Health USA Inc.CattleNADA 043-141
Equizole Horse Wormer Pelletsapproval voluntarily withdrawnThiabendazoleBoehringer Ingelheim Animal Health USA Inc.HorsesNADA 044-654
TBZ Wormer Paste 50%approval voluntarily withdrawnThiabendazoleBoehringer Ingelheim Animal Health USA Inc.CattleNADA 048-487
TBZ Wormer Paste 43%approval voluntarily withdrawnThiabendazoleBoehringer Ingelheim Animal Health USA Inc.CattleNADA 049-461
Equizole 50% Wormer Paste; Equizole 50% Wormer Paste For Horsesapproval voluntarily withdrawnThiabendazoleBoehringer Ingelheim Animal Health USA Inc.HorsesNADA 098-689

Species are the major species the Green Book search lists for the application ("—" where it lists another species or none). Approval dates are not part of the Green Book listing files and are not shown. Pioneer applications (NADA) come first, then generics (ANADA).

Questions about thiabendazole reports

How many adverse event reports has FDA received for thiabendazole?

56 reports record a drug with thiabendazole as its active ingredient in the openFDA release of 28 Sep 2026, covering reports received through March 2026. 0 of them arrived in the latest 12 months.

Which brand do these reports concern?

That cannot be known from the public data. openFDA masks brand and manufacturer names in adverse event records, so the reports counted here cannot be attributed to a particular brand. The Green Book lists 17 approved applications with this ingredient alone; the reference list on this page names them without any counts.

What signs are reported most often?

uncoded sign (25%), death (8.9%), dropper, Abnormal (8.9%), eye irritation (8.9%) and caps, Abnormal (7.1%). These are the coded terms listed in reports; several can appear in one report, and a term's presence is not a finding that the drug was responsible.

Which species and breeds appear in these reports?

dog (37.5%), human exposure (14.3%) and cat (12.5%). Among single-breed animals the most frequent labels are Domestic Shorthair, Brahman, Akita and Bulldog; popular breeds appear often in any drug's reports because there are more of them.

Are reports rising?

0 reports in the 12 months to March 2026, and none in the 12 months before. FDA posts reports quarterly with a delay of three to six months, so the newest months are incomplete and usually grow in later releases. Counts also move with sales, publicity and time on the market.

Do these reports show that thiabendazole harms pets?

Report counts cannot show that. FDA states that "there is no certainty that the reported drug or device caused the adverse event" and that the event "may have been related to an underlying disease, other drugs used at the same time or other non-drug related sources." FDA also notes that commonly used products may have more reports simply because more animals receive them.

Are these the side effects of thiabendazole?

They are signs listed in reports, not an established list of side effects. The adverse reactions observed in studies are printed on each product's FDA-approved label, which a veterinarian can go through with you. This page is a record of what was reported to FDA.

How do I report a problem with an animal drug?

FDA asks owners and veterinarians to call the drug company first (the number is on the label); companies must pass reports to FDA. Reports can also go directly to FDA on Form FDA 1932a. See the guide on how to report.

Where this comes from. Counts are built from the openFDA Animal & Veterinary adverse event bulk files released 28 Sep 2026, which hold reports FDA's Center for Veterinary Medicine received through 31 Mar 2026. openFDA masks brand and manufacturer names in these files, so drugs are counted by the active ingredients each record discloses and no figure is attributed to a brand, application or company. Ingredient names, and the separate reference lists of approved products, follow the FDA Green Book as of 1 Oct 2026. Drug entries are grouped by the active ingredients their unmasked ingredient field discloses; the application number that records also carry is not used. No report text, lot numbers or reporter details are published. See the methodology and sources; FDA's record is authoritative, and corrections are handled within five working days.